Disposition of bulkheads in oil-carrying ships



Jan. 22, 1929. 1,e9,7o9

C. ONO

DISPOSITION OF BULKHEADS IN OIL CARRYING SHIPS Filed June 5, 1928 2 Sheets-Sheet l a vwentoz I c. ONO

DISPOSITION OF BULKHEADS IN OIL CARRYING SHIPS Jan. 22, 1929. 1,699,709

Filed June 1928 2 Sheets-Sheet 2 Qwuemtoz: C 0/70 E1315 Gwynne/1 Patented den. 22, 1929.

DISPOSITION OF BULKHEADS IN OIL-CARRYING SHIPS.

Application filed June 5, 1928, Serial No. 283,073, and in Japan June 21, 1927.

This invention relates to improvements in steel ships carrying bulk-oil and other fluid cargoes in holds and its objects are, by means of the proposed disposal of longitudinal bulkheads, to minimize the shifting of the cargo in holds Which is peculiar to this class of ships, to make the construction and its oiltight work easier, to make it simpler to lay pipes for working liquid cargo, and to make more eflicient and economical general functions of the ships of this class as compared with existing types of ships.

Fig. 1 shows a midship section of existing type of ships for carrying bulk-oil andother fluid'bulk cargo.

Fig. 2 shows a midship section of another class which in recent years has a tendency to be adopted in Europe.

Figs. 3 and 4 show the midship sections of ships according to this invention and in which Fig. 3 shows an example suitable for heavy oil or molasses, while Fig. 4 shows an example suitable for light or refined oil.

Fig. 5 is a midsh'ip section of a modification of an oil or other fluid cargo carrier acraw or heavy oil carrier, and dotted line showing light or refined oil carriers with trunk on. upper deck.

"When compared with ordinary cargo ships, hulk oil carriers must have many features in construction and disposition of bulkheads, etc., so that many requirements therefor shall be fulfilled. Among these requirements, the following are the most important ones and are related to this invention: (1) to check the tendency of increase of rolling of the ship due to shift of oil to one side as the ship rolls and also to prevent both its overflow and increase of the pressure due to the expansion caused by the rise of temperature in oil itself; to have sufficient stability at fullload while she must not be to stiff, that is, her centre of gravity must not be too low at lightdoad; (3) to enable to make easy adjustment of loading by filling or emptying small spaces in order to keep the load-lines assigned in various localities and seasons as well as for cargoes of different qualities and denitiesg generally to make the construction simple as possible (though a large capacity in 7 one tank is undesirable) and yet to lessen the number of tanks, thus simplifying the installation of pipes and vents; and (5) to reduce unsupported spans so that lighter material an be used to save the weight of material in construction, and also that the excessive stress on a few rivets causing leaks can be avoided. 7

In Fig. 1 showing a midship section of oil carriers of steel construction of ordinary sys tem, 1 and 1 are shell plating; 2 and 2 upper deck; 3 the centre longitudinal bulkhead extending from the ships bottom to the upper deck; 4 and 4: second deck; 5 and 5 side longitudinal bulkheads. The spaces enclosed by 4, 5, a part of 2 and a part of 1 are called summer tanks. The spaces between 3 and 5 form expansion trunks. In loading fluid cargo, the free-surface of the fluid must be at a certain height in these spaces: The dotted lines 7 and 7' show a position of the free surface of fluid when the ship is vertical and inclined respectively. 6 and 6 are expansive hatchways for the summer tanks.

From the consideration of special features requisite for this class of ships, the present existing type has many defects. For requirement 1) stated above, the centre longitudinal bulkhead and the expansion trunks may be considered to fulfil this function, but cording to this invention; full line showing a often due to leakage from air valves and pipes there is a dangerous tendency of the free-surface of the fluid to fall below 't-hesecend deck, and thereby of suddenly increasing the extent of the surface whichnecessitates man-on-watch to examine tanks and to use his extreme care to watch any leakage in pipe system sons to properly distribute the load into various compartments. For these purposes, there is commonly'provided in such a shi "tanks of excessive volume against a limitec deadweight carrying capacity, accompanied excessive amount of oil tight work.

For requirement (2), in the existing type of ships'the free-surface of the fluid is limited in height and for keeping sufficient stability at full-load condition, there is a necessity of comparatively"large beam, which increases cost oft-he construction. And again at lightload it is'usual custom to fill some of main oil tanks with ballast in order to keep .sutlicieut draught and trim. Butin this condition,

= stability of the ship is liable to be too great,

causing excessive rolling. The usual arrangement of summer tanks does not suit for ballast tanks and if they are once used, they are very ditlicult to clean out.

For requirement 3) the summer tanks are aimed to do this function. But in the present system of construction, as it is, they are too large for actual requirements, and conllO sequently their disposition and construction are complicated.

'For (4) requirement, the existing system of construction and disposition is not simple enough to be convenient for ship-builders generally, the system shown in Fig. 2 being designed to make certain improvements on the existing one.

For (5) requirement, there exists in the ordinary arrangement of the present system a great unsupported span and area such as the centre longitudinal bulkheads. Here the second deck and side longitudinal bulkheads are in positions of merely hanging down from the upper deck and usually receive pressure from only one side, which will give chances for leakage due to excessive stress,

In the'system shown in Fig. 2, numerals in-. dicating parts of the hull correspond to those in Fig. 1.

This design undoubtedly removes some of the defects enumerated in relation to from (1) to (5) requirements. Yet the side longitudinal bulkheads, as they approach to the ends of the ship, are with difliculty connected with the ships side and other parts. In respect to the 1) and (2) requirements there is no improvements at all, and with regards to (5) requirement the side longitudinal bulkhead will cause more troubles as compared with the former.

Ships shown in Figs. 3 and 4 of this invention removes the detects existing in the prevailing types of bulk-oil carriers.

In the figures shown, 1 and 1 are steel plates; 2 and 2 upper deck; 3 centre longitudinal bulkhead; 5 and 5 side longitudinal inclining bulkheads, which form a summer tank inside with a narrow bottom t. These bulkheads form a Y shaped construction together with lower centre longitudinal bulkhead, and strongly unite the upper partof the ship to the bottom. The spaces on both sides of this Y shaped construction are main oil tanks, while the spaces between the summer tank sides and outside shell perform the function of expansion trunks, so that the danger of sudden falling of the free-surface of the fluid in tanks below the second deck of ordinary types is entirely removed, which undoubtedly satisfies 1) requirement.

For (2) requirement, there is no danger in regulating the height of tree-surface of the fluidin the main tank. The sun11ner=-tanl is situated in a position similar to that of a cantilever system so that cleaning out of the ballast in it can be easily effected by a pipe laid at the narrow bottom of the tank.

For 3) requirement, the size of the summer tank of this invention is not limited as that of the ordinary system, and the volume ratio of the summer tank and the main oil tank can be easily adjusted so as to eliminate the necessity of providing unnecessary and excessive empty space.

space,

pipe connection between the main tank and the summer tank, and also their operating rods 11 and 12. In the known systems, such operating rods must be assembled in three groups, while in this invention they can be arranged on only one line.

For (5) requirement, the Y-shaped longi tudinal construction symmetrical to the centre line of'ship, the main idea of this invention, offers not only great resistance for longitudinal bending, but also for transverse resistance. The unsupported span and area of bulkheads in this system as compared with the prevailing system are much smaller and consequently there is no need of stifl'ening bulkheads in two directions, i. e. transverse and longitudinal, so that one or the other as the case may be can be dispensed with.

Moreover, the transverse bulkheads are divided into small parts by Y-shaped longitudinal bulkheads, and if stiffeners are properly arranged according to shape and area of each they will become comparatively smaller and lighter as compared with the other system. At the same time, it makes the construction easy and occasions for leakage far less.

In the example shown in Fig. 5, in place of a single line centre bulkhead, two lines of longitudinal bulkheads are brought down to the bottom of ship from corners of the bottom of the summer tank, so that a tunnel is formed by an inside space between them, and in it are installed all of pipes for oil, steam, vents, and controlling spindles for valves. This tunnel is made sufliciently large for men to pass through in order to have inspections and repairs to all parts.

In this figure, the parts indicated by 1, 2, 4 and 5 correspond to those in the examples shown in 3 and 4. 3 and 3 are two longitudinal vertical bulkheads on both sides of the centre line of ship. The stiffeners on 3 and i, 5 and 5 are fitted to oil tank sides. so that caulking can be done even when the main oil tanks are lilled. (1i and (i are main oil pipes; 7 branch pipe in oil tank; 8 and 9 sluice valves: and 10 controlling spindle for Valve. Apparatus for valve handlings may consist of controlling spindle, bevel gear and rods. Valve handles may be installed in the pump room. Valves and pipes of the summer tank may be fitted so as to lead the oil into the tankeither by the independent longitudinal pipe line or by the main line. 12is a platform in the tunnel. One can easily understand that many advantages such as thereto at any time, or concentration of main part of maneuvering gears into pump room etc. can be obtained by the last example.

To sum up, this invention satisfies almost all requirements for this class of ships or bulk-oil carriers, removing the defects existing in the prevailing system, and brings superior results compared with old one.

I claim:

1. In steel ships carrying bulk oil and other fluid cargoes, the disposition of Y- shaped longitudinal construction comprising longitudinal inclining bulkheads forming a summer tank with a narrow bottom at upper half of centre line of ship, and a longitudihad Vertical bulkhead extending therefrom to the ships bottom to build up a centre longitudinal bulkhead, substantially as shown and described.

2. In steel ships carrying bulk oil and other fluid cargoes, the disposition of Y-shaped longitudinal construction comprising longitudinal inclining side bulkheads forming a summer tank with a narrow bottom at upper half of centre line of ship, and doubled longitudinal vertical bulkheads extending therefrom to the ships bottom to build up a longitudinal tunnel, substantially as shown and described.

In testimony whereof he aflixes his signature. V

' CHOZO ONO. 

